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000
FXUS65 KBOU 232342
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
542 PM MDT Tue Apr 23 2024

.KEY MESSAGES...

- Scattered showers and a few storms diminishing as they move east
  this evening.

- Stormier weather pattern in the works, starting late Thursday
  and peaking next weekend, with accumulating moderate snowfall
  in the mountains.

- Stronger storms possible northeast plains Thursday
  afternoon/evening.

&&

.SHORT TERM /Through Wednesday/...
Issued at 259 PM MDT Tue Apr 23 2024

Not much change to the forecast at this hour. Weak convection from
a little QG lift and diurnal heating over the mountains is
progressing eastward. There`s about 500 J/kg CAPE in the
mountains, enough for a few lightning strikes, but this should
decrease in an elevated mixed layer as it moves east across the
plains while the surface air should remain capped. We backed off
the PoPs for the eastern portion of the plains a bit more with
doubts about how much will be left when it gets there.

Skies gradually clear overnight, though there may still be some
clouds on the northern and eastern borders early Wednesday
morning. We`ll have warmer and drier air aloft, and should see
less convection. Still probably some cumulus and some light
showers over the northern mountains. There`s a small chance (10%)
of generating a storm or two on a Denver cyclone boundary in the
late afternoon, but we probably won`t quite be warm/moist enough.
Convergence may force some brief updrafts that don`t sustain
themselves. Current forecast and guidance temperatures look good.

&&

.LONG TERM /Wednesday night through Tuesday/...
Issued at 259 PM MDT Tue Apr 23 2024

A series of mid-level systems will bring multiple rounds of
precipitation throughout northeastern Colorado starting Thursday
through this weekend. As high pressure pushes eastward Wednesday
night, winds aloft shift southwest. A shortwave trough enters
western Colorado and mid-level moisture deepens from the
mountains to the plains Thursday morning. 700mb temperatures
remain warm ranging from 3-7 C/km which should lead to the warmest
day this week. Surface temperatures Thursday afternoon for the
mountains and valleys reach 49-60F while temperatures in the
plains and urban corridor increase near 70-80F. As the trough
enters our region, daytime heating and mid-level QG ascent should
allow for a few showers to develop in the foothills and northeast
plains early Thursday afternoon. MLCAPE values increase amongst
all guidance between 800-900 J/kg with pockets of higher values in
the northeastern corner. Additional, favorable SFC-3km wind shear
of 30-40kts and mid-level lapse rates between 7-8 C/km could lead
to an environment for scattered to numerous thunderstorms to
develop across the plains along with the potential for a few
embedded severe storms producing small hail. As DCAPE values
approach 1000 J/kg, expect storms to produce wind gusts up to
45-60 mph. These conditions persist through late Thursday evening
before exiting into Nebraska/Kansas. The highest threat of severe
storms exist mainly for the areas along and above I-76 through
Thursday night.

Our unsettled pattern continues Friday and there is a consensus
amongst guidance indicating wind aloft shift northwesterly. This
will allow additional moisture and surface winds to increase
across the mountains and plains. Scattered showers and storms are
possible Friday afternoon but with the lack of instability,
expecting these storms to be less robust leading to quick heavy
rainfall and lightning. This weekend as an additional shortwave
trough arrives from the western US coast. In terms of the severe
threat, atmospheric conditions of weak low level shear and MLCAPE
between 100-300 J/kg may lead to scattered to numerous showers
versus thunderstorms both Saturday and Sunday. In terms of
Saturday, precipitable water values increase over GFS and ECMWF
ensembles with the highest values mainly near the northeastern
corner reaching 0.50- 0.80 inches. Although conditions may change
leading up to Saturday, the atmosphere seems fitting for a heavy
rainfall threat throughout the plains. Across the other side of
the Divide, increasing QPF fields will likely lead to periods of
light to moderate snowfall for the mountains starting early
Saturday morning for areas above 8.5k ft. This may lead to winter
weather headlines depending on snow levels and uptick in QPF
values this weekend.

&&

.AVIATION /00Z TAFS through 00Z Wednesday/...
Issued at 538 PM MDT Tue Apr 23 2024

VFR through the TAF period with generally SCT-BKN mid-level
clouds. Main challenge will be winds in the near-term period, with
a Denver Cyclone located between APA and BKF. This has slowly
drifted north-northeast over the past couple of hours, with gusty
north/northwest winds on the backside of the circulation (APA),
with some sort of east or northeast at DEN. A few weak showers on
radar have also been noted, which have spit out just enough
outflow to occasionally shift winds to the north at DEN/BJC.

Expect these weak showers and the cyclone itself to weaken over
the next few hours with drainage flow returning after sunset
tonight. Weak flow is expected tomorrow, maintaining some sort of
southeast component through most of the day. A couple of high-
based showers are possible again tomorrow, but coverage at this
point looks sparse enough that VCSH wasn`t included.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

SHORT TERM...Gimmestad
LONG TERM...AD
AVIATION...Hiris